The approaches described in this section are approaches that could be pursued, but not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated, the approaches described in this section may not be prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
In the testing of wafer-based semiconductor devices, probe cards are typically used to provide electrical interconnection between a testing system and the semiconductor wafer. Such probe cards may, for example, include a printed circuit board (i.e., PCB), a probe substrate, and an interposer, e.g., a pogo pin or spring pin based interposer) providing electrical interconnection between the PCB and the probe substrate. Resilient probe elements are supported by the probe substrate. For example, in certain probe cards, the probe elements may be held in a “floating” configuration within a probe head adjacent the probe substrate. In other probe cards, the probe elements may be fixed at one end to a conductive region, e.g., a conductive trace, a terminal, a lead, a contact pad, etc.) of the probe substrate.
Probe elements may have different configurations, depending upon the testing application. For example, cantilever style probes are sometimes used in the testing of memory devices. Vertically configured probes, e.g., probe needles) are often used in tighter pitch probe cards, such as area array configurations.
Probe elements may be fabricated using a wide variety of techniques. For example, probe elements may be fabricated using semiconductor fabrication masking techniques. This may include forming probe elements on a sacrificial substrate that is destroyed after the probe elements are formed to separate the probe elements from the substrate. An alternative is to first form a release layer, such as a thin copper layer, on a substrate and then form the probe elements on the release layer using masking techniques. After the probe elements are formed, the release layer is destroyed, for example by etching, to release the probe elements from the substrate.